Antenna module

Abstract

To provide an antenna module whose module size in a plane direction can be reduced while the decrease in antenna characteristic is suppressed.SOLUTION: An antenna module 1 includes a first substrate 10 including a power supply line 141 to a first antenna element 111 and a second antenna element 121 and handling high-frequency signals in a milli-wave zone, a second substrate disposed overlapping with a part of the first substrate 10 in a plan view and handling a base band signal in a frequency band lower than the high-frequency signal, and a metal housing 30 including a first accommodation space 30A to accommodate RFIC, a second accommodation space 30B to accommodate BBIC, and a blocking wall 50 provided between the first accommodation space 30A and the second accommodation space 30B. The blocking wall 50 is disposed overlapping with the power supply line 141 in a plan view. At least one of the blocking wall 50 and the first substrate 10 includes a non-interference part 60 that reduces the interference between the blocking wall 50 and the power supply line 141.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an antenna module. [Background technology]

[0002] The following Patent Document 1 discloses a wireless module that transmits and receives high-frequency signals (RF signals). This wireless module includes a first board that handles high-frequency signals in the millimeter wave band, a second board that handles baseband signals with a lower frequency than the high-frequency signals, and a housing that houses the first board and the second board. The first board and the second board are connected to each other while partially overlapping each other, which reduces the module size in the planar direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7309089 Summary of the Invention [Problem to be solved by the invention]

[0004] The first board is provided with an RFIC (Radio-Frequency Integrated Circuit) that processes high-frequency signals, and the second board is provided with a BBIC (Baseband Integrated Circuit) that processes baseband signals. Since the RFIC and the BBIC interfere with each other electromagnetically when they are close to each other, the housing is provided with a partition (shielding wall).

[0005] In an array antenna, the feeder lines from the RFIC to each antenna must be the same length. Therefore, the RFIC is often placed in the center of the first board in a plan view. For this reason, the first board usually has a feeder line that extends toward the second board.

[0006] In this configuration, if the overlap between the first and second substrates is increased to further miniaturize the module, the power feed line extending from the RFIC to the second substrate may overlap the partition in a plan view, which may cause the partition to come close to the power feed line and adversely affect the power feed line, resulting in a deterioration in antenna characteristics.

[0007] The present invention has been made in consideration of the above problems, and has an object to provide an antenna module that can reduce the module size in the planar direction while suppressing deterioration of antenna characteristics. [Means for solving the problem]

[0008] An antenna module according to a first aspect of the present invention comprises a first substrate including an antenna element and a feeder line to the antenna element, the first substrate being arranged to overlap a portion of the first substrate in a plan view and being electrically connected to the first substrate at the overlapping portion, the second substrate being arranged to handle a baseband signal in a frequency band lower than the high frequency signal, and a metal housing to which the first substrate and the second substrate are attached, the first substrate having a first mounting surface facing the metal housing, the first substrate having a first mounting surface facing the metal housing, the second ... a first IC electrically connected to the first substrate is provided, and a second IC for processing the baseband signal is provided on a second mounting surface of the second substrate facing the metal housing; the metal housing includes a first accommodating space for accommodating the first IC, a second accommodating space for accommodating the second IC, and a shielding wall provided between the first accommodating space and the second accommodating space, the shielding wall is arranged to overlap the power feed line in a planar view, and at least one of the shielding wall and the first substrate is provided with a non-interference portion for reducing interference between the shielding wall and the power feed line.

[0009] According to the first aspect of the present invention, since the first board and the second board are connected while partially overlapping each other, the module size in the planar direction can be reduced. In addition, since a shielding wall of a metal case is provided between the first IC mounted on the first board and the second IC mounted on the second board, electromagnetic interference between the first IC and the second IC can be avoided. In addition, it is possible to prevent unnecessary radiation from the first IC and the second IC from leaking to the outside. Furthermore, even if the shielding wall is arranged to overlap with the power feed line of the first board in a plan view, at least one of the shielding wall and the first board is provided with a non-interference portion that reduces interference between the shielding wall and the power feed line, so that the presence of the shielding wall is less likely to adversely affect the power feed line, and deterioration of the antenna characteristics can be suppressed.

[0010] A second aspect of the present invention is an antenna module of the first aspect, wherein the shielding wall comprises a contact surface that contacts the first mounting surface, and a tunnel portion formed on the contact surface and extending along the power supply line, and the tunnel portion may form the non-interference portion.

[0011] A third aspect of the present invention is the antenna module according to the second aspect, wherein a cross section of the tunnel portion is semicircular, and a diameter of the cross section of the tunnel portion is larger than a width of the power feed line.

[0012] A fourth aspect of the present invention is the antenna module according to the third aspect, wherein a diameter of the tunnel portion is greater than three times a width of the feed line.

[0013] A fifth aspect of the present invention is the antenna module according to either the third or fourth aspect, wherein a diameter of the tunnel portion may be smaller than 1 / 10 of the wavelength of unwanted radiation.

[0014] A sixth aspect of the present invention is an antenna module according to any one of the first to fifth aspects, wherein the first substrate has a ground layer on the first mounting surface side of the power supply line, and the ground layer may form the non-interference portion. Effect of the Invention

[0015] According to the above aspect of the present invention, it is possible to provide an antenna module that can reduce the module size in the planar direction while suppressing deterioration of antenna characteristics. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional configuration diagram of an antenna module according to a first embodiment. [Diagram 2] FIG. 2 is an enlarged view of an area A shown in FIG. [Diagram 3] 2 is a bottom perspective view of region B shown in FIG. 1. [Figure 4] 11 is a cross-sectional view of a main part of an antenna module according to a second embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Antenna modules according to embodiments of the present invention will now be described with reference to the drawings.

[0018] (First embodiment) Fig. 1 is a cross-sectional configuration diagram of an antenna module 1 according to a first embodiment. Fig. 2 is an enlarged view of an area A shown in Fig. 1. Fig. 3 is a bottom perspective view of an area B shown in Fig. 1. As shown in FIG. 1, the antenna module 1 according to this embodiment includes a first substrate 10, a second substrate 20, and a metal housing 30. The first substrate 10 includes a first insulating film 22 and a second insulating film 23. The second insulating film 22 is a metal housing 30.

[0019] The first substrate 10 is formed into a rectangular plate shape in a plan view. The first substrate 10 handles high frequency signals (RF signals) in the millimeter wave band. The second substrate 20 is formed into a rectangular plate shape in a plan view. The second substrate 20 handles baseband signals (BB signals) in a frequency band lower than the high frequency signals. The first substrate 10 and the second substrate 20 are attached to the metal housing 30 in a partially overlapping state in a plan view.

[0020] In the following description, an XYZ orthogonal coordinate system is set, and the positional relationship of each component may be described with reference to this XYZ orthogonal coordinate system. As shown in Fig. 1, the Z-axis direction is set in the planar direction in which the first substrate 10 and the second substrate 20 overlap. The X-axis direction and the Y-axis direction are set in the planar direction along the plate surfaces of the first substrate 10 and the second substrate 20.

[0021] For convenience of explanation, in the Z-axis direction, the first substrate 10 side (+Z side) relative to the second substrate 20 will be referred to as the upper side, and the metal housing 30 side relative to the second substrate 20 will be referred to as the lower side (-Z side). Note that it is not necessary for the first substrate 10 to be on the upper side in the direction of gravity, and the metal housing 30 to be on the lower side in the direction of gravity.

[0022] The first substrate 10 has an RFIC 11 (first IC) provided on a bottom surface 10a (first mounting surface) facing the metal housing 30. The first substrate 10 also has an inter-substrate connection section 40 provided on the bottom surface 10a. Other electronic components (not shown) may be provided on the top surface 10b of the first substrate 10. The RFIC 11 generates a predetermined high-frequency signal from a baseband signal supplied from the second substrate 20, for example. The first substrate 10 performs not only transmission processing but also reception processing of the high-frequency signal.

[0023] The first substrate 10 is a multilayer substrate having a plurality of conductor layers, as shown in Fig. 2. Specifically, the first substrate 10 includes conductor layers arranged in the following order from top to bottom: a first layer 110, a second layer 120, a third layer 130, and a fourth layer 140. An insulator 200 such as a liquid crystal polymer is provided between the first layer 110, the second layer 120, the third layer 130, and the fourth layer 140.

[0024] The first layer 110 is a first antenna layer, on which a plurality of first antenna elements 111 (unpowered elements) are formed. The first antenna elements 111 are arranged in an array. The second layer 120 is a second antenna layer, on which a second antenna element 121 (powered element) is formed and arranged below the first antenna element 111. The first antenna element 111 and the second antenna element 121 function as antennas.

[0025] The third layer 130 forms a ground layer 131 that is electrically grounded. An opening 132 is formed in the ground layer 131. The fourth layer 140 is a signal layer, and a power feed line 141 is formed therein. The power feed line 141 is electromagnetically coupled (e.g., capacitively coupled) to the second antenna element 121 through the opening 132 of the third layer 130. This coupling enables the first substrate 10 to radiate a high-frequency signal supplied from the power feed line 141 from the second antenna element 121 and the first antenna element 111, and to output a high-frequency signal received by the second antenna element 121 and the first antenna element 111 to the power feed line 141. The antenna configuration is not limited to this, and may be one in which the power supply line 141 and the second antenna element 121 are electrically and physically connected, or one in which the first antenna element 111 (parasitic element) is not present.

[0026] The power feed line 141 is provided on an inner layer of the first substrate 10. In other words, the power feed line 141 is not exposed on the lower surface 10a of the first substrate 10, and the lower side of the power feed line 141 is covered with an insulator 200. On the other hand, the first layer 110 (first antenna element 111) is covered with a protective film 210. The protective film 210 is preferably a low-loss dielectric that does not adversely affect the transmission and reception of high-frequency signals. In addition, the protective film 210 may have a role of improving the gain of high-frequency signals.

[0027] 1, the second substrate 20 has a BBIC 21 (second IC) provided on a bottom surface 20a (second mounting surface) facing the metal housing 30. Note that other electronic components (not shown) are provided on the top surface 20b of the second substrate 20 in addition to the inter-substrate connection portion 40 and the external connection portion 41. The BBIC 21 is connected to an external device (not shown), for example, via the external connection portion 41, and generates a predetermined baseband signal based on a command from the external device.

[0028] The inter-board connection part 40 is disposed in an overlap region L where the first substrate 10 and the second substrate 20 overlap in a plan view. The inter-board connection part 40 is a connector that mechanically and electrically connects the first substrate 10 and the second substrate 20 in the Z-axis direction. The inter-board connection part 40 connects the +X side end of the lower surface 10a of the first substrate 10 to a portion of the upper surface 20b of the second substrate 20 closer to the center (BBIC 21) than the -X side end.

[0029] 1, by connecting the first substrate 10 and the second substrate 20 in a partially overlapping manner, the module size in a planar direction (for example, the X-axis direction) can be reduced. It is preferable that no electronic components other than the inter-substrate connection part 40 are disposed between the first substrate 10 and the second substrate 20 in the overlap region L, specifically, on the lower surface 10a of the first substrate 10 and the upper surface 20b of the second substrate 20 in the overlap region L. This reduces the gap between the first substrate 10 and the second substrate 20, and reduces the module size in a planar direction (the Z-axis direction).

[0030] 1, the metal housing 30 includes a bottom wall 31, a peripheral wall 32, and a shielding wall 50. The bottom wall 31 has a rectangular shape in a plan view extending in the X-axis direction and the Y-axis direction. The peripheral wall 32 has a rectangular frame shape in a plan view along the outer periphery of the bottom wall 31. The peripheral wall 32 extends upward (to the +Z side) from the outer periphery of the bottom wall 31. Part of the outer periphery of the first substrate 10 and the second substrate 20 is attached to the upper end of the peripheral wall 32.

[0031] The shielding wall 50 forms a first housing space 30A for housing the RFIC 11 and a second housing space 30B for housing the BBIC 21 inside the bottom wall 31 and the peripheral wall 32. The shielding wall 50 extends in the Y-axis direction between the RFIC 11 and the BBIC 21, and is connected to each of the inner walls of the peripheral wall 32 that face each other in the Y-axis direction. The shielding wall 50 also extends upward (to the +Z side) from the bottom wall 31. A step surface 50a that supports the lower surface 20a of the second substrate 20 is formed at the upper end of the shielding wall 50.

[0032] A first heat dissipation section 33 is formed in the first housing space 30A. The first heat dissipation section 33 extends from the bottom wall 31 toward the upper side (+Z side) and is in contact with the RFIC 11 via a heat dissipation sheet (not shown). A second heat dissipation section 34 is formed in the second housing space 30B. The second heat dissipation section 34 extends from the bottom wall 31 toward the upper side (+Z side) and is in contact with the BBIC 21 via a heat dissipation sheet (not shown).

[0033] 2, a contact surface 51 that comes into contact with the lower surface 10a of the first substrate 10 is formed at the upper end of the shielding wall 50. A tunnel portion 52 extending in the X-axis direction along the power feed line 141 is formed at the contact surface 51. The tunnel portion 52 forms a non-interference portion 60 that reduces interference between the shielding wall 50 and the power feed line 141. Note that the interference referred to here is interference that may affect the antenna characteristics of the antenna module 1, and includes some or all of electrical, electromagnetic, and mechanical interference.

[0034] 3, a plurality of power supply lines 141 are connected to the RFIC 11. The power supply lines 141 extending from the RFIC 11 toward the second substrate 20 side (+X side) overlap with the shielding wall 50 in a plan view. For this reason, a tunnel portion 52 (non-interference portion 60) is formed in the shielding wall 50.

[0035] The tunnel portion 52 is formed in a semicircular shape in cross section along the YZ plane. The diameter of the tunnel portion 52 is larger than the width of the power feed line 141. Preferably, the diameter of the tunnel portion 52 is larger than three times the width of the power feed line 141. Also, preferably, the diameter of the tunnel portion 52 is smaller than 1 / 10 of the wavelength of the unwanted radiation.

[0036] In other words, when the diameter of the tunnel portion 52 is D, the width of the feed line 141 is W, and the wavelength of the unwanted radiation is λ, it is desirable to satisfy the following relational expression (1). 3W < D < λ / 10 …(1) For example, when the frequency of the source signal of the RFIC 11 is 20 GHz, λ=1 / 20 GHz=15 mm. When W=0.2 mm, D is 0.6 mm or more and 1.5 mm or less.

[0037] 2, if the thickness T of the insulator 200 below the power feed line 141 is sufficiently large, the interference between the shielding wall 50 and the power feed line 141 can be reduced even without the tunnel portion 52. In this case, the insulator 201 below the power feed line 141 in the insulator 200 becomes the non-interference portion 60. Even if the thickness T is zero, the interference between the shielding wall 50 and the power feed line 141 can be reduced by forming the tunnel portion 52 and satisfying the above relational expression (1).

[0038] As described above, the antenna module 1 according to this embodiment includes the first substrate 10 including the second antenna element 121 and the power feeder 141 to the second antenna element 121, and handling high-frequency signals in the millimeter wave band; the second substrate 20 that is arranged to overlap a part of the first substrate 10 in a planar view and is electrically connected to the first substrate 10 at the overlapping part, and that handles baseband signals in a frequency band lower than the high-frequency signals; and a metal housing 30 to which the first substrate 10 and the second substrate 20 are attached. The first substrate 10 includes, on a bottom surface 10a facing the metal housing 30, a power feeder 141 for processing high-frequency signals. 41, and the second substrate 20 is provided with a BBIC 21 for processing baseband signals on a bottom surface 20a facing the metal housing 30. The metal housing 30 has a first accommodating space 30A for accommodating the RFIC 11, a second accommodating space 30B for accommodating the BBIC 21, and a shielding wall 50 provided between the first accommodating space 30A and the second accommodating space 30B, and the shielding wall 50 is arranged to overlap with the power supply line 141 in a planar view. At least one of the shielding wall 50 and the first substrate 10 has a non-interference portion 60 for reducing interference between the shielding wall 50 and the power supply line 141.

[0039] According to this configuration, the first substrate 10 and the second substrate 20 are connected in a partially overlapping manner, so that the module size in the planar direction can be reduced. In addition, the shielding wall 50 of the metal housing 30 is provided between the RFIC 11 mounted on the first substrate 10 and the BBIC 21 mounted on the second substrate 20, so that electromagnetic interference between the RFIC 11 and the BBIC 21 can be avoided. In addition, it is possible to prevent unnecessary radiation from the RFIC 11 and the BBIC 21 from leaking to the outside. Furthermore, even if the shielding wall 50 is arranged to overlap the power feed line 141 of the first substrate 10 in a planar view, at least one of the shielding wall 50 and the first substrate 10 is provided with a non-interference portion 60 that reduces interference between the shielding wall 50 and the power feed line 141, so that the presence of the shielding wall 50 has less adverse effect on the power feed line 141, and deterioration of the antenna characteristics can be suppressed.

[0040] In the present embodiment, the shielding wall 50 includes a contact surface 51 that contacts the lower surface 10a of the first substrate 10, and a tunnel portion 52 that is formed on the contact surface 51 and extends along the power feed line 141, and the tunnel portion 52 forms a non-interference portion 60. According to this configuration, even if the thickness T of the insulator 200 cannot be sufficiently secured below the power feed line 141, the formation of the tunnel portion 52 can suppress deterioration of the antenna characteristics.

[0041] In the present embodiment, the cross section of the tunnel portion 52 is semicircular, and the diameter of the cross section of the tunnel portion 52 is larger than the width of the power supply line 141. This configuration can prevent the shielding wall 50 (the inner wall of the tunnel portion 52) from coming into contact with the power supply line 141.

[0042] In this embodiment, the diameter of the tunnel portion 52 is greater than three times the width of the power feeder 141. With this configuration, a sufficient space can be secured on both sides of the power feeder 141 in the width direction, thereby suppressing degradation of the antenna characteristics.

[0043] In this embodiment, the diameter of the tunnel portion 52 is smaller than 1 / 10 of the wavelength of the unwanted radiation. With this configuration, it is possible to block signals having the unwanted radiation wavelength.

[0044] Second embodiment Next, a second embodiment of the present invention will be described. In the following description, the same or equivalent configurations as those in the above-described embodiment are given the same reference numerals, and the description thereof will be simplified or omitted.

[0045] Fig. 4 is a cross-sectional view of a main part of an antenna module 1' according to the second embodiment. Note that Fig. 4 illustrates a portion corresponding to Fig. 2 described above. As shown in FIG. 4, the antenna module 1′ of the second embodiment differs from the above-described embodiments in that the first substrate 10 has a ground layer 151 on the lower surface 10a side (in this embodiment, the lower surface 10a) of the power supply line 141, and the ground layer 151 forms a non-interference portion 60.

[0046] The first substrate 10 of the second embodiment further includes a fifth layer 150 as a conductor layer in addition to the first layer 110, the second layer 120, the third layer 130, and the fourth layer 140. The fifth layer 150 is disposed below (on the -Z side of) the fourth layer 140, and an insulator 200 is provided between the fourth layer 140 and the fifth layer 150. Note that the fifth layer 150 shown in FIG. 4 is exposed on the lower surface 10a of the first substrate 10, but may be covered by the insulator 200.

[0047] The fifth layer 150 has a ground layer 151 that is electrically grounded. The ground layer 151 may be a so-called solid pattern in which no openings 132 are formed, unlike the ground layer 131 of the third layer 130. According to this configuration, the ground layer 151 disposed between the shielding wall 50 and the power feed line 141 can ensure isolation between the shielding wall 50 and the power feed line 141, thereby suppressing deterioration of the antenna characteristics.

[0048] Although preferred embodiments of the present invention have been described and illustrated above, it should be understood that they are illustrative of the present invention and should not be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Thus, the present invention should not be considered as limited by the foregoing description, but rather by the scope of the claims.

[0049] For example, although the cross section of the tunnel portion 52 has been described as being semicircular, the cross section of the tunnel portion 52 may be rectangular.

[0050] In addition, within the scope of the spirit of the present invention, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, and the above-described embodiments and variations may be combined as appropriate. [Explanation of symbols]

[0051] 1 Antenna Module 10 First substrate 10a Bottom surface (first mounting surface) 10b Top side 11 RFIC (First IC) 20 Second substrate 20a Bottom surface (second mounting surface) 20b Top surface 21 BBIC (Second IC) 30 Metal case 30A First storage space 30B Second storage space 31 Bottom wall 32 Peripheral wall 33 First heat dissipation section 34 Second heat dissipation section 40 Board-to-board connection 41 External connection part 50 Shielding Wall 50a step surface 51 Contact surface 52 Tunnel Section 60 Non-interference section 110 1st layer 111 first antenna element (antenna element) 120 2nd layer 121 Second antenna element 130 3rd layer 131 Ground Layer 132 Opening 140 4th layer 141 Power line 150 5th layer 151 Ground Layer 200 Insulator 201 Insulators 210 Protective film L overlap area

Claims

1. a first substrate including an antenna element and a feeder line to the antenna element, the first substrate handling a high frequency signal in the millimeter wave band; a second substrate disposed to overlap a portion of the first substrate in a plan view, electrically connected to the first substrate at the overlapping portion, and handling a baseband signal having a frequency band lower than that of the high frequency signal; a metal housing to which the first substrate and the second substrate are attached; a first IC that processes the high-frequency signal and is electrically connected to the power supply line is provided on a first mounting surface of the first substrate that faces the metal housing; the second substrate has a second mounting surface facing the metal housing, the second IC being configured to process the baseband signal; The metal housing is a first accommodation space for accommodating the first IC; a second accommodation space for accommodating the second IC; a shielding wall provided between the first storage space and the second storage space, the shielding wall is disposed so as to overlap with the power supply line in a plan view, At least one of the shielding wall and the first substrate includes a non-interference portion that reduces interference between the shielding wall and the power supply line. Antenna module.

2. The shielding wall is a contact surface that contacts the first mounting surface; a tunnel portion formed on the contact surface and extending along the power supply line; The tunnel portion forms the non-interference portion. The antenna module according to claim 1 .

3. The cross section of the tunnel portion is semicircular, and the diameter of the cross section of the tunnel portion is larger than the width of the power supply line. The antenna module according to claim 2 .

4. The diameter of the tunnel portion is greater than three times the width of the power supply line. The antenna module according to claim 3 .

5. The diameter of the tunnel portion is smaller than 1 / 10 of the wavelength of the unwanted radiation. The antenna module according to claim 3 .

6. the first substrate includes a ground layer on the first mounting surface side of the power supply line, The ground layer forms the non-interference portion.

6. An antenna module according to claim 1.

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